“填充无效,无法删除"使用 AesManaged [英] "Padding is invalid and cannot be removed" using AesManaged
问题描述
我正在尝试使用 AesManaged 进行简单的加密/解密,但是在尝试关闭解密流时我不断收到异常.这里的字符串被正确加密和解密,然后在 Console.WriteLine 打印正确的字符串后,我得到 CryptographicExceptionPadding was invalid and cannot be removed".
I'm trying to get simple encryption/decryption working with AesManaged, but I keep getting an exception when trying to close the decryption stream. The string here gets encrypted and decrypted correctly, and then I get the CryptographicException "Padding was invalid and cannot be removed" after Console.WriteLine prints the correct string.
有什么想法吗?
MemoryStream ms = new MemoryStream();
byte[] rawPlaintext = Encoding.Unicode.GetBytes("This is annoying!");
using (Aes aes = new AesManaged())
{
aes.Padding = PaddingMode.PKCS7;
aes.Key = new byte[128/8];
aes.IV = new byte[128/8];
using (CryptoStream cs = new CryptoStream(ms, aes.CreateEncryptor(),
CryptoStreamMode.Write))
{
cs.Write(rawPlaintext, 0, rawPlaintext.Length);
cs.FlushFinalBlock();
}
ms = new MemoryStream(ms.GetBuffer());
using (CryptoStream cs = new CryptoStream(ms, aes.CreateDecryptor(),
CryptoStreamMode.Read))
{
byte[] rawData = new byte[rawPlaintext.Length];
int len = cs.Read(rawData, 0, rawPlaintext.Length);
string s = Encoding.Unicode.GetString(rawData);
Console.WriteLine(s);
}
}
推荐答案
诀窍是使用 MemoryStream.ToArray()
.我还更改了您的代码,以便在加密和解密时使用 CryptoStream
进行写入.并且您不需要显式调用 CryptoStream.FlushFinalBlock()
,因为您在 using()
语句中有它,并且该刷新将在 Dispose 上发生()
.以下对我有用.
The trick is to use MemoryStream.ToArray()
.
I also changed your code so that it uses the CryptoStream
to Write, in both encrypting and decrypting. And you don't need to call CryptoStream.FlushFinalBlock()
explicitly, because you have it in a using()
statement, and that flush will happen on Dispose()
. The following works for me.
byte[] rawPlaintext = System.Text.Encoding.Unicode.GetBytes("This is all clear now!");
using (Aes aes = new AesManaged())
{
aes.Padding = PaddingMode.PKCS7;
aes.KeySize = 128; // in bits
aes.Key = new byte[128/8]; // 16 bytes for 128 bit encryption
aes.IV = new byte[128/8]; // AES needs a 16-byte IV
// Should set Key and IV here. Good approach: derive them from
// a password via Cryptography.Rfc2898DeriveBytes
byte[] cipherText= null;
byte[] plainText= null;
using (MemoryStream ms = new MemoryStream())
{
using (CryptoStream cs = new CryptoStream(ms, aes.CreateEncryptor(), CryptoStreamMode.Write))
{
cs.Write(rawPlaintext, 0, rawPlaintext.Length);
}
cipherText= ms.ToArray();
}
using (MemoryStream ms = new MemoryStream())
{
using (CryptoStream cs = new CryptoStream(ms, aes.CreateDecryptor(), CryptoStreamMode.Write))
{
cs.Write(cipherText, 0, cipherText.Length);
}
plainText = ms.ToArray();
}
string s = System.Text.Encoding.Unicode.GetString(plainText);
Console.WriteLine(s);
}
另外,我猜你知道你会想要明确设置 模式 AesManaged 实例,并使用 System.Security.Cryptography.Rfc2898DeriveBytes 从密码和盐派生密钥和 IV.
Also, I guess you know you will want to explicitly set the Mode of the AesManaged instance, and use System.Security.Cryptography.Rfc2898DeriveBytes to derive the Key and IV from a password and salt.
另见:
- AesManaged
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